JPH08246900A - Combustor and turbine operating method for gas or liquid fuel turbine - Google Patents

Abstract

(57) [PROBLEMS] To provide a combustor and a gas or liquid fuel turbine that suppress the generation amount of pollutants and have an efficient cooling mechanism. SOLUTION: At least 50% of the air supplied to the combustor 1 by a compressor is mixed with a fuel to produce a lean air-fuel mixture, and the remaining air is utilized for shock cooling, The spent shock-cooled air is injected as a radial jet into the post-primary combustion zone 17 through the perforations 6 formed in the wall 2.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to combustors for gas or liquid fuel turbines and methods of operating such turbines.

[0002]

Gas or liquid fuel turbine plants are
It is usually equipped with an air compressor, a combustor and a turbine.
The compressor supplies pressurized air to a combustor, a portion of the air is mixed with fuel in a combustor mixing zone, and the air-fuel mixture (hereinafter also simply referred to as "mixture") is in a primary combustion zone. Combustion is used to create combustion gas for driving the turbine. Another portion of the air supplied by the compressor is typically used to cool the hot surfaces of the combustor.

The proportion of air mixed with the fuel determines the temperature range in which combustion occurs and affects the amount of pollutants, especially NOx and CO, produced by combustion. That is, the fuel rich mixture (i.e., the mixture having a relatively low proportion of air) burns at a relatively high temperature and produces a relatively large amount of NOx and CO. Since high temperatures are detrimental to component life, large amounts of cooling air are required to keep temperatures downstream of the primary combustion zone low.

When the amount of air mixed with the fuel is increased, the fuel is burned at a relatively low temperature to produce a lean mixture (a fuel-lean air-fuel mixture) with a small amount of pollutants, but the air mixed with the fuel is mixed. The greater the amount, the less air is available to achieve the cooling required to maintain a reasonable component life. Therefore, burning a lean mixture means that the resulting use of available cooling air must be made efficient.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a combustor which suppresses the amount of pollutants generated in use and which has an efficient cooling mechanism, and a gas or liquid fuel turbine. is there.

[0006]

In order to solve the above problems, according to one aspect of the present invention, a gas or liquid fuel turbine having a compressor for supplying air to a combustor for combustion and cooling. A mixing zone for mixing fuel with a portion of the air supplied to the combustor;
It includes a primary combustion zone provided downstream of the mixing zone and a post-primary combustion zone provided downstream of the primary combustion zone, and the primary combustion zone and the post-primary combustion zone are both impact (collision) cooled. Is formed on the inside of a wall that is cooled by the post combustion zone having means for injecting a plurality of cooling air jets transverse to the flow of combustion gases, said portion of air being A combustor is provided that is configured to account for at least 50% of the air supplied to the combustor.

In a preferred embodiment, the wall is
It has a plurality of holes that extend to surround the post-primary combustion zone and allow used shock cooling air to be used as the cooling air jet. A plurality of perforations (a series of perforations) for directing air into the post-primary combustion zone can be formed in an area of the wall that defines the post-primary combustion zone. Air directed into the post-primary combustion zone preferably flows radially into the post-primary combustion zone with respect to the longitudinal axis of the combustor. Taper lip (tapered lip) in each hole
Can be formed.

In a preferred embodiment, the air flowing into the post-primary combustion zone is at least 700 ° C, and in some circumstances at least 800 ° C. The jet of spent shock-cooled air entering the post-primary combustion zone is mixed with combustion gas in the post-primary combustion zone to establish a substantially uniform radial temperature distribution in the post-primary combustion zone. It is preferable to configure so that

According to another aspect of the invention, a method of operating a gas or liquid fuel turbine, wherein compressed air is supplied to a combustor for combustion and cooling, and a portion of the air supplied to the combustor. Mixed with fuel in the combustor mixing zone,
Another portion of the air supplied to the combustor is used to cool the walls of the combustor's primary combustion zone by impact cooling, and the spent impact cooling air is then used downstream of the primary combustion zone in the post-primary combustion zone. Directing a plurality of jets of cooling air transversely to the flow of combustion gas such that said portion of the air occupies at least 50% of the air supplied to said combustor. Provided.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. In general, combustor size and morphology are determined by the overall turbine design and power requirements. Typically, multiple combustors are arranged around the axis of the turbine. The combustor 1 illustrated by way of example is a generally cylindrical or "can" type having a longitudinal axis 100, mounted in a compressed air enclosure opening into a turbine casing and evenly spaced around the turbine. One of four or more combustors that have been burned.

An air compressor (hereinafter also simply referred to as “compressor”) (not shown) is driven by a compressor turbine which is exposed inside each combustor 1 and is driven by combustion gas. The compressor turbine is axially connected to each stage of the compressor that supplies compressed air to the combustor for combustion and cooling.

More specifically, each combustor 1 comprises a concentric inner cylindrical wall 2 and an outer cylindrical wall 3. The walls 2 and 3 are separated from each other so as to define an annular space or passage 30 between them. The inner wall 2 is generally non-perforated except for a plurality of holes or perforations 6 arranged in a ring in the illustrated embodiment. Each hole 6 is formed with a tapered lip 36 to assist in forming cooling air in the form of a jet, as described below, and to stiffen (increase rigidity) the wall 2.

The outer wall 3 has a large number of perforations 7, 27 distributed in an annular or spiral fashion over its surface. These perforations provide impact cooling to the inner wall 2 by impinging a thin jet of compressed air (ie, high pressure air) on the inner wall 2. As shown, the perforations 7 are located upstream of the dilution holes 6 (as described below) and the perforations 27 are located downstream of the dilution holes 6.

A fuel injection assembly 11 is attached to the left end (that is, the downstream end) of the walls 2 and 3 via a conical duct 8. The fuel injection assembly 11 comprises an air swirl generator 12 having a number of ducts 10 that impart both a radial velocity component and a circumferential velocity component to an air flow 13.
Region 15 is a mixing zone where the air flowing through duct 10 mixes with the fuel axially injected by fuel injector 11. Although not specifically shown, the fuel injection port itself is usually provided in a ring attached to the rear plate. A first primary combustion zone 25 is formed immediately downstream of the mixing zone 15. The boundary between both bands 15 and 25 is not distinct, but is shown by a wavy line.

As mentioned above, the combustor is enclosed entirely within the compressed air enclosure such that air enters the combustor through respective holes or ducts in the combustor. Depending on the location of the holes or ducts, it performs a combustion or cooling function. In a typical prior art shock cooled combustor, approximately 20% of the total air supplied to the combustor is carried through a swirl generator and the rest is used for cooling.

In contrast, in the arrangement according to the invention, a very high proportion of the available air is used to produce the air-fuel mixture, so that a very lean air-fuel mixture is present in the mixing zone 15. Is generated. In the present invention, at least 50% of the air supplied to the combustor is fuel injector 1
It is intended to be used for direct mixing with fuel from 1. and under certain circumstances very advantageous results can be obtained when the amount of air directly mixed with the fuel is 57% of the total air. It was confirmed to be obtained.

By producing an air-fuel mixture with such a high proportion of available air, the air-fuel mixture is burned at a lower temperature in conventional combustors and thus pollutants, CO and The amount of NOx generated can be suppressed. Of course, the higher the proportion of air used for the initial air-fuel mixture, the less proportion of air is available to cool the combustor. However, since combustion takes place at low temperatures, that in part makes up for the reduction in the amount of air used for cooling. Further, the combustor of the present invention has a cooling mechanism that is particularly efficient in utilizing available cooling air as described below. Moreover, the cooling air incinerates (burns out) CO in the combustion gas as described later.
Used to.

Inside the combustor 1 downstream of the first primary combustion zone 25, the primary combustion zone 16 extending from the mixing zone 15, the rear primary combustion zone 17, and the transition zone 18 in which almost no combustion occurs are arranged in this order from the downstream side. Make up. Transition band 18
Communicates with a combustor outlet 19, which communicates with an inlet to a turbine driven by the combustion gases created in the combustor 1.

As mentioned above, at least 50% of the air supplied by the compressor is mixed zone 15 of each combustor 1.
Directly mixed with fuel in. The rest of the air exhibits a special flow pattern as described below. That is, the air flowing along and around the outer wall 3 impinges on the inner wall 3 through the perforations 7, 27 as indicated by the arrow 20, thereby causing the combustor 1 and more particularly the In other words, the primary combustion zone 16 of the inner wall 2 and the post-primary combustion zone 1
Impact cooling is applied to the area surrounding 7. The air flowing into the annular space 30 between the walls 2 and 3 flows along the inner wall 2 as indicated by the arrows 21, 31 and reaches a relatively large hole 6 drilled in the inner wall. As indicated by arrow 22, the spent shock-cooling air is in the form of a series of jets radially in the embodiment relative to the axis 100, i.e. transverse to the flow of combustion gases from the primary combustion zone 16. At a high velocity and with considerable force, it flows into the post-primary combustion zone 17,
Mix with combustion gases. The mixing of this air (air blown at a high speed with a considerable force) and the combustion gas (combustion products) flowing from the zone 16 to the zone 17 serves to provide a substantially uniform radial temperature distribution. And provide a residence time in zone 17 sufficient to reduce, ie incinerate, the pollutant CO produced in the combustion process, and the transition zone 18 is also not as long as in zone 17, but it does Provides a residence time that is reduced.

The temperature at the location after the spent impact coolant (air) is jetted into the primary combustion zone 17 is such that quenching of the combustion products (ie, excessive cooling) does not occur. Must be configured to be Otherwise (if excessive cooling of the combustion products occurs), no further CO will be incinerated. This temperature should not drop below 700 ° C, ideally at least 80 ° C.
It has been found that it should be 0 ° C. Introducing spent shock-cooled air into the post-primary combustion zone 17 with sufficient force / velocity and at an appropriate temperature requires careful design of the walls 2,3 and the perforations 6,7,27. It

Therefore, in order to obtain the desired result, ie controlled combustion to reduce the amount of pollutants produced,
In order to achieve effective cooling of the combustor and uniform radial temperature distribution of the combustion products downstream of the primary combustion zone 16, the perforations 7 on the outer wall 3 and the inlet holes 6 on the inner wall 2 are provided. The number, size and location are selected to suit the particular environmental conditions in which the combustor is operated and to ensure the required amount and velocity of air flowing through holes 6.

The shock cooling of the invention disclosed herein is fundamentally different from the conventional cooling structure in which the spent coolant is injected axially along the inner surface of the wall 2 of the combustion zone. The walls 2 and 3 defining the transition zone 18 can incorporate additional cooling means if desired. For example, although the walls are shown as a single wall, they can be double walls or other structures. In that case, thin film or impact (impact) cooling can be used.

[Brief description of drawings]

FIG. 1 is an axial cross-sectional view of a gas turbine combustor according to the present invention.

[Explanation of symbols]

 1: Combustor 2: Inner cylindrical wall 3: Outer cylindrical wall 6: Hole or perforation 7: Hole or perforation 11: Combustion injector 12: Air vortex Genesis 15: Mixing zone 16: Primary combustion zone 17: Rear primary combustion zone 18: Transition primary combustion zone 25: Pre-combustion zone 27: Hole or perforation 30: Annular space or passage 36: Tapered lip 100: Longitudinal axis

Claims (12)

[Claims] 1. A combustor for a gas or liquid fuel turbine having a compressor for supplying air to the combustor for combustion and cooling, wherein a portion of the air supplied with fuel to the combustor. A mixing zone to be mixed with, a primary combustion zone provided downstream of the mixing zone, and a post-primary combustion zone provided downstream of the primary combustion zone, the primary combustion zone and the post-primary combustion zone, Together, they are formed inside the wall cooled by impact cooling, the post-primary combustion zone having means for injecting a plurality of cooling air jets transverse to the flow of combustion gases, A combustor configured to occupy at least 50% of the air supplied to the combustor. 2. The wall has a plurality of holes extending so as to surround the post-primary combustion zone and allow spent shock cooling air to be used as the cooling air jet. The combustor according to claim 1, wherein: 3. A plurality of perforations for directing air into the post-primary combustion zone are formed in an area of the wall that defines the post-primary combustion zone. The combustor according to Item 1 or 2. 4. The air directed into the post-primary combustion zone is adapted to flow into the post-primary combustion zone in a radial direction with respect to a longitudinal axis of the combustor. Or the combustor according to item 3. 5. The combustor according to claim 2, 3 or 4, wherein a tapered lip is formed in each of the holes. 6. The combustor according to claim 2, wherein the air flowing into the post-primary combustion zone is configured to be at least 700 ° C. 7. The combustor according to claim 6, wherein the air flowing into the post-primary combustion zone is configured to have a temperature of at least 800 ° C. 8. The jet of spent shock-cooling air entering the post-primary combustion zone is mixed with combustion gases in the post-primary combustion zone to provide a substantially uniform radial direction within the post-primary combustion zone. The combustor according to any one of claims 2 to 7, wherein the combustor is configured to set the temperature distribution of. 9. A method of operating a gas or liquid fuel turbine, wherein compressed air is supplied to a combustor for combustion and cooling, and a portion of the air supplied to the combustor is mixed zone of the combustor. Mixed with fuel within, and another portion of the air supplied to the combustor is used to cool the walls of the primary combustion zone of the combustor by shock cooling, and the spent shock cooled air is then used to cool the wall. Directing downstream of the primary combustion zone into the primary combustion zone transversely to the flow of combustion gases as a plurality of cooling air jets, said portion of air directing at least 50% of the air supplied to the combustor. A method characterized by occupying. 10. The method of claim 9 wherein the air entering the post-primary combustion zone is at least 700 ° C. 11. The air flowing into the post-primary combustion zone is at least 800 ° C.
The method described in. 12. The jet of spent shock cooling air flowing into the post-primary combustion zone is mixed with combustion gases in the post-primary combustion zone to provide a substantially uniform radial direction in the post-primary combustion zone. 12. The method according to claim 9, wherein the temperature distribution is set.